Pedro Robot Arm

Pedro is a fully open-source, 3D-printable educational robot arm designed for STEM classrooms and makers who want to learn robotics from scratch. With only four printable parts, four mini servo motors, and tool-free snap-together assembly, Pedro can be built and operational in under 10 minutes.Design Philosophy

Source: https://github.com/mattions/pedro

Pedro is intentionally minimal. The entire structure consists of four 3D-printed components — BASE, ARM, GEAR, and SERVO bracket — that snap and gear together without screws or adhesive. This makes it ideal for workshops where dozens of students can assemble their own robot simultaneously. All parts print in under 2 hours on any FDM printer at 0.2mm layer height in PLA or ABS.

Electronics

Pedro is powered by a custom Arduino-compatible controller board called the Pedro Board, which integrates four servo outputs, an nRF24L01 radio module for wireless control, an HC-05 Bluetooth module for smartphone connectivity, and an ESP8266 for WiFi and IoT integration. Power comes from a 7.4V LiPo battery rechargeable via USB.

Control Modes

Pedro supports five control modes: Manual (serial/USB from a PC), Radio (nRF24L01 remote), Bluetooth (smartphone app), Replay (execute recorded sequences), and Record (capture and store movement sequences). The firmware is built on the Arduino platform and is fully open source under Apache 2.0 in the PedroRobot repository.

Community

Pedro is used in over 70 schools and educational workshops across France and internationally. The project ecosystem includes Pedro Board (PCB gerbers + schematics), PedroRobot (Arduino firmware), and PedroSTEM (complete lesson plans and activities). All repositories are published under Apache 2.0 by Almoutazar Saandi.

Printing

Print files match the upstream source repository (github.com/mattions/pedro, Pedro_3D/) one-to-one — all nine parts are byte-identical to the repo.

Structural parts (print 1 each):

• Base_Servo.stl — base / shoulder servo mount
• Elbow_Servo.stl — elbow servo mount
• Wrist_Servo.stl — wrist servo mount
• Wrist.stl — wrist joint
• End_Point.stl — end effector / tool point
• file8.stl, file9.stl — remaining structural links (repo ships these under generic names)

Mirror pair (print both, not alternates):

• ForeArm_Left.stl + ForeArm_Right.stl — the two halves of the forearm; both are required.

Servos: 4 × Tower Pro SG90 9g micro servos (base, shoulder, elbow, wrist). The Pedro Board PCB (or an Arduino Uno/Nano substitute) and all electronics are sourced from the BOM, not printed.

Cleanup note: Four extra files (BASE.stl, SERVO.stl, ARM.stl, GEAR.stl) were removed — they are not present in the cited source repo, their byte sizes did not match any repo part (e.g. GEAR.stl was an anomalous 7.6 MB), and the hero photo shows the multi-part repo design rather than the four-piece snap-together variant described in the older marketing text above. Keeping them would have over-printed parts from a different design.